Approximately 190,000 new cases of prostate cancer will be diagnosed in the U.S. in 2003, and this year 30,400 American men will die from prostate cancer. In the United States, the annual cost of treating prostate cancer has reached $1.72 billion. While there are a significant number of potential courses for treating prostate cancer, a single "best treatment" has not yet emerged, especially for managing early prostate cancer. Many current therapies have significant attendant side effects and/or risks associated with them. For this reason, continued effort has been expended toward development of minimally invasive means of targeting early-localized prostate cancer. In this Phase II SBIR application, we propose to develop and test a system for magnetic resonance imaging (MRI) guided laser ablation of localized prostate cancer. The system will use multiple interstitial laser delivery probes to effect targeted treatment volumes in the prostate. A laser/computer workstation precisely controls the deposition of laser energy based on processing of real-time temperature sensitive MR images acquired during therapy. An advanced Visualization and control interface will allow the user to specify and update therapeutic targets during treatment. This system will be tested in a canine tumor model of prostate cancer. Based on our prior experience, we believe that this system will offer an improvement in treatment of prostate cancer through minimally invasiveness, improved targeting accuracy, and feedback of real-time information about treatment progression.